/*
 * FreeRTOS Kernel V10.5.1
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 */

#include <stdlib.h>

/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining
 * all the API functions to use the MPU wrappers.  That should only be done when
 * task.h is included from an application file. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

#include "FreeRTOS.h"
#include "list.h"

/* Lint e9021, e961 and e750 are suppressed as a MISRA exception justified
 * because the MPU ports require MPU_WRAPPERS_INCLUDED_FROM_API_FILE to be
 * defined for the header files above, but not in this file, in order to
 * generate the correct privileged Vs unprivileged linkage and placement. */
#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE /*lint !e961 !e750 !e9021. */


void vListInitialise(List_t * const pxList)
{
    /* The list structure contains a list item which is used to mark the
     * end of the list.  To initialise the list the list end is inserted
     * as the only list entry. */
    pxList->pxIndex = (ListItem_t *) &(pxList->xListEnd);

    listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE(&(pxList->xListEnd));

    /* The list end value is the highest possible value in the list to
     * ensure it remains at the end of the list. */
    pxList->xListEnd.xItemValue = portMAX_DELAY;

    /* The list end next and previous pointers point to itself so we know
     * when the list is empty. */
    pxList->xListEnd.pxNext = (ListItem_t *) &(pxList->xListEnd);
    pxList->xListEnd.pxPrevious = (ListItem_t *) &(pxList->xListEnd);

    /* Initialize the remaining fields of xListEnd when it is a proper ListItem_t */
    #if (configUSE_MINI_LIST_ITEM == 0)
    {
        pxList->xListEnd.pvOwner = NULL;
        pxList->xListEnd.pxContainer = NULL;
        listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE(&(pxList->xListEnd));
    }
    #endif

    pxList->uxNumberOfItems = (UBaseType_t)0U;

    /* Write known values into the list if
     * configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    listSET_LIST_INTEGRITY_CHECK_1_VALUE(pxList);
    listSET_LIST_INTEGRITY_CHECK_2_VALUE(pxList);
}

void vListInitialiseItem(ListItem_t * const pxItem)
{
    /* Make sure the list item is not recorded as being on a list. */
    pxItem->pxContainer = NULL;

    /* Write known values into the list item if
     * configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE(pxItem);
    listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE(pxItem);
}

/**
 * pxNewListItem插入到链表的尾部
 */
void vListInsertEnd(List_t * const pxList, ListItem_t * const pxNewListItem)
{
    ListItem_t * const pxIndex = pxList->pxIndex;

    /* Only effective when configASSERT() is also defined, these tests may catch
     * the list data structures being overwritten in memory.  They will not catch
     * data errors caused by incorrect configuration or use of FreeRTOS. */
    listTEST_LIST_INTEGRITY(pxList);
    listTEST_LIST_ITEM_INTEGRITY(pxNewListItem);

    /* Insert a new list item into pxList, but rather than sort the list,
     * makes the new list item the last item to be removed by a call to
     * listGET_OWNER_OF_NEXT_ENTRY(). */
    pxNewListItem->pxNext = pxIndex;
    pxNewListItem->pxPrevious = pxIndex->pxPrevious;

    /* Only used during decision coverage testing. */
    mtCOVERAGE_TEST_DELAY();

    pxIndex->pxPrevious->pxNext = pxNewListItem;
    pxIndex->pxPrevious = pxNewListItem;

    /* Remember which list the item is in. */
    pxNewListItem->pxContainer = pxList;

    (pxList->uxNumberOfItems)++;
}

/**
 * 将pxNewListItem插入到pxList升序链表
 * xItemValue为键值,元素从小到大排列
 */
void vListInsert(List_t * const pxList, ListItem_t * const pxNewListItem)
{
    ListItem_t * pxIterator;
    const TickType_t xValueOfInsertion = pxNewListItem->xItemValue;

    /* Only effective when configASSERT() is also defined, these tests may catch
     * the list data structures being overwritten in memory.  They will not catch
     * data errors caused by incorrect configuration or use of FreeRTOS. */
    listTEST_LIST_INTEGRITY(pxList);
    listTEST_LIST_ITEM_INTEGRITY(pxNewListItem);

    /* Insert the new list item into the list, sorted in xItemValue order.
     *
     * If the list already contains a list item with the same item value then the
     * new list item should be placed after it.  This ensures that TCBs which are
     * stored in ready lists (all of which have the same xItemValue value) get a
     * share of the CPU.  However, if the xItemValue is the same as the back marker
     * the iteration loop below will not end.  Therefore the value is checked
     * first, and the algorithm slightly modified if necessary.
     */
    if(xValueOfInsertion == portMAX_DELAY)
    {
        pxIterator = pxList->xListEnd.pxPrevious;
    }
    else
    {
        /* 遍历找到链表插入的位置 */
        pxIterator = (ListItem_t *) &(pxList->xListEnd);
        while (pxIterator->pxNext->xItemValue <= xValueOfInsertion)
            pxIterator = pxIterator->pxNext;
    }

    pxNewListItem->pxNext = pxIterator->pxNext;
    pxNewListItem->pxNext->pxPrevious = pxNewListItem;
    pxNewListItem->pxPrevious = pxIterator;
    pxIterator->pxNext = pxNewListItem;

    /* Remember which list the item is in.  This allows fast removal of the
     * item later.
     */
    pxNewListItem->pxContainer = pxList;

    (pxList->uxNumberOfItems)++;
}

/**
 * 删除pxItemToRemove节点
 */
UBaseType_t uxListRemove(ListItem_t * const pxItemToRemove)
{
    /* The list item knows which list it is in.  Obtain the list from the list
     * item.
     * 找到节点所在的链表
     */
    List_t * const pxList = pxItemToRemove->pxContainer;

    pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
    pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;

    /* Only used during decision coverage testing. */
    mtCOVERAGE_TEST_DELAY();

    /* Make sure the index is left pointing to a valid item. */
    if(pxList->pxIndex == pxItemToRemove)
    {
        pxList->pxIndex = pxItemToRemove->pxPrevious;
    }

    pxItemToRemove->pxContainer = NULL;
    (pxList->uxNumberOfItems)--;

    /* 返回剩余节点数 */
    return pxList->uxNumberOfItems;
}
